Dick Cheney once jokingly referred to himself as Darth Vader - such was his dark reputation with the mainstream US media. With the departure of Karl Rove on Friday, George W. Bush's electoral mastermind, the US vice-president is seen as "the last man standing" in the administration.

Yet far from being the increasingly isolated figure that he is often portrayed, Mr Cheney wields influence that has arguably never been greater. Among the close circle of trusted advisors that Mr Bush has relied on since coming to the White House, only Mr Cheney remains.